Hot water system

ABSTRACT

Apparatus and control therefor senses the temperature of water at a hot water line discharge point and, upon activation, causes the line to drain until water of a preselected temperature reaches the discharge point. Further apparatus is provided in combination to blend warm water of an initial preselected temperature with cooler water in a predetermined proportion to provide a continuing discharge of warm water in a comfortable temperature range for human convenience.

United States Patent 1 Hock [ 1 May 27, 1975 HOT WATER SYSTEM [76] Inventor: Walter L. Hock, 7539 Kolmar Ave., Skokie, 111. 60076 [22] Filed: Jan. 7, 1974 [21] Appl. No.: 431,357

[52] US. Cl. 137/115; 137/334; 137/624.2, 251/132 [51] Int. Cl. F16k 19/00 [58] Field of Search 137/115, 334, 337, 606, 137/624.l2; 236/12 A, 93 R; 251/132 [56] References Cited UNITED STATES PATENTS 2,842,155 7/1958 Peters 137/337 2,991,481 7/1961 Book 137/606 UX 3,450,159 6/1969 Wilken.... 137/606 3,505,692 4/1970 Forbes 251/132 X 2/1972 Kopp 137/606 3/1974 Maddren 137/337 X Primary Examiner-R0bert G. Nilson Attorney, Agent, or Firm-Fitch, Even, Tabin & Luedeka [57] ABSTRACT Apparatus and control therefor senses the temperature of water at a hot water line discharge point and, upon activation, causes the line to drain until water of a preselected temperature reaches the discharge point. Further apparatus is provided in combination to blend warm water of an initial preselected temperature with cooler water in a predetermined proportion to provide a continuing discharge of warm water in a comfortable temperature range for human convenience.

5 Claims, 5 Drawing Figures HOT WATER SYSTEM The present invention generally relates to apparatus for providing warm water, and more particularly, relates to apparatus and control therefor for providing warm water within a preselected temperature range at a water line discharge point. As used herein, the term line refers to any conduit or piping for conveying a fluid. I

The illustrated embodiment of the present invention is particularly adapted for use in homes or commmercial buildings wherein water lines discharge into lavatory sinks located both separately and in combination with bathtubs and showers that are provided for human convenience. Such water line discharge points are usually connected to both hot and cold water pipes, and the water discharge is controlled manually through a faucet in each line, or through a blending faucet common to both lines. From the faucet, the water discharges into a catch basin of the fixture and thence to a drain. In the typical building or home installation, the water lines are contained in walls or floors and distribute the water to various commonly known discharge points. Usually in the instance of the hot water line, the hot water source is a conventional hot water supply tank, and this tank may be located between about and about 120 feet away from the various discharge points. This run is sometimes even longer.

The principles of heat transfer are well-known in the art and need not be reviewed in detail herein. It is sufficient for purposes of background to mention only a few generalizations. For example, the hot water will lose heat in accordance with a number of variables, among which are the conduit material, surrounding insulation, temperature differential with the ambient, and the length of the line from the hot water source to the point of discharge. The longer the line, the greater the area through which heat may be transferred. Such transfer or heat flow is usually more pronounced during the winter or under other conditions of greater temperature difference between the hot and cold sides of the substance through which the heat is transferred. It is generally during periods of nonuse when the water stands in the line that the result of heat transfer is noticed the most, for after such a period a person can readily sense that the hot water has become cooler. In general, the reverse of the foregoing is true for the cold water line.

Thus, the heat transfer of either line is in the direction that will establish equilibrium with the surrounding conditions of the line. Although heat transfer may be significant during the aforementioned periods of nonuse, some heat transfer occurs during flow of water through its conduit. These basic considerations are examined more fully hereinafter.

As a consequence of the foregoing, a user of water often bleeds or drains the line of the initial water standing therein, especially if the contemplated use involves personal contact with the water. For example, upon arising in the morning, a user desiring warm water for washing will turn on the hot water faucet and allow the water to discharge until it reaches the desired temperature at the faucet. While waiting, the user will probably sample the temperature of the water several times and then blend it with cold water, either through a blending type faucet or in a stopped bowl. This personal time and attention given by the user delays his use of the water, and he may experience considerable discomfort before water of a comfortable temperature is available for use. Thereafter, he may have difficulty maintaining the comfortable temperature because of a likely further temperature increase of the hot water until the temperature of the water in the line substantially reaches the temperature of the water in the supply tank. The supply tank water generally ranges in temperature between about 140F to about 160F, which range is too hot for direct human use. Thus more time and effort are needed to blend the water until the temperature is stabilized to that which is comfortable and desirable as perceived by the human senses. It has been determined that the temperature range that provides the greatest personal comfort is between about F and about F. Hereinafter, water within this temperature range will be referred to as being within the comfort range.

Thus, a person generally works with an unpredictable blend of water until he perceives that the temperature of the water in the lines has stabilized. The result is personal inconvenience, a likely personal discomfort, and a likely excess use of water.

It is a primary object of the present invention to provide a system to facilitate draining of cool water from a hot water line until water of a desired initial temperature is reached at discharge point.

It is another object of the present invention to provide apparatus and control therefor that drains a hot water line of cool water in a manner that both reduces the time and conserves the water in reaching a desired temperature of the water at a faucet.

It is a further object of the present invention to provide a system wherein hot water of a preselected initial temperature is mixed in a predetermined proportion with cooler water to provide a warm blend within a predetermined human comfort range at a water discharge point.

These and other objects of the present invention are more particularly set forth in the following detailed description and in the accompanying drawings illustrating a preferred embodiment of the present invention of which:

FIG. 1 is a view in elevation of a lavatory having connected thereto apparatus and control therefor employing principles of the present invention;

FIG. 2 is a fragmentary plan view of a portion of the apparatus of FIG. 1;

FIG. 3 is a view in elevation of a control housing and some control devices contained therein taken along the line and in the direction indicated by 33 of FIG. 1;

FIG. 4 is a view in elevation of the control housing of FIG. 3 and taken along the line and in the direction indicated by 44 of FIG. 1; and

FIG. 5 is an electrical schematic diagram of an operating circuit of the apparatus of FIG. 1.

Briefly, a hot water system 9 is illustrated that is particularly adapted for use in conjunction with a conventional lavatory sink 11 which has a faucet 13 connected in common to a hot water line 15 and a cold water line 17. The lavatory sink l1 empties into a drain 19. A housing 21 contains control circuitry and devices for the apparatus of the system that is described in detail hereinafter. A control and indicator station 23 is connected to the apparatus of the housing 21 and is disposed, for example, above the lavatory sink 11 in an adjacent wall.

The system is actuated by a momentary depression of a start switch 25 of the control and indicator station 23. Water in the hot water line then bypasses the faucet 13 and discharges directly into the drain 19 until the temperature of the water in the hot water line reaches a predetermined point, whereupon the water ceases to flow and a ready indicator light 27 is energized. The only personal attention required of the user is to initiate the operation. In accordance with the principles of the invention, this condition is achieved in less time than by a manual control and monitoring of a faucet discharge and with less water expended.

During non-use, the water in the system cools while standing in the pipes through heat flow to the surrounding elements in accordance with well-known principles of heat transfer, and when the temperature of the water drops below the predetermined point, the ready light is de-energized. The control circuit then returns to its normal, or preoperative, state and remains in readiness for a further operating cycle.

Preferably, the system includes a faucet 13 of the type that blends hot and cold water and indicates the proportion of each by appropriate indicia on the faucet handle. Then in accordance with further principles of the present invention, a setting of the faucet is determinable that will blend hot and cold water so as to pro duce a continuing flow of warm water at a comfortable temperature, the duration of the flow at such temperature being limited primarily by the capacity of the primary hot water heater of the system.

The usual operation of the faucet 13 is not interfered with if the start switch is not actuated. On the other hand, if the start switch is actuated and the ready light does not appear, which might occur, for example, in instances where there is no hot water in the primary hot water heater, the illustrated embodiment provides for automatically cancelling the cycle initiated by the actuation of the start switch after a predetermined lapse of time. Moreover, there is provision for cancelling the cycle manually by the depression of a momentary cancel button 29.

A shower line or bathtub line or both could be included in the illustrated system 9 to thereby extend the advantages of the present system. For purposes of illustration and description, however, only the representative lavatory sink 11 is shown, it being understood that the principles of the invention are applicable as well to other plumbing fixtures and combinations thereof.

More particularly, the lavatory sink 11 receives hot water through control devices and plumbing apparatus contained in the housing 21 from a conventional primary hot water tank (not shown).

The hot water enters the illustrated embodiment through a convenience valve 31, the water being delivered thereto from the primary heater (not shown) by piping (not shown) contained in the walls and floors. Similarly, the cold water is received through a convenience valve 33. The hot water line 15 is broken into several segments. A segment 35 leads from the convenience valve 31 to apparatus in the housing 21, a segment 37 leads from the apparatus in the housing 21 to the faucet 13, and a segment 39 leads from the apparatus in the housing 21 to the drain 19.

Preferably, the faucet 13 is of the single-lever blending valve type in which the cold and hot water lines 17 and 37 respectively are connected to the input ports 41 and 43 respectively of the faucet 13. The faucet 13 is provided with a single lever or operating handle 45 which is used to manually control the proportions of hot and cold water being blended and discharged from a single discharge port 47 of the faucet. It is also preferred that the faucet 13 have indicia on the operating handle 45 to indicate the proportion of hot and cold water being blended by the faucet 13. This indicia may be in the form of a color coded scale, such as has been heretofore manufactured by the Speakman Company of Wilmington, Delaware, under the registered trademark COLORTEMP. In such instance, red indicates the hottest water and blue indicates the coldest water. This color indicia is exposed, for example, through a viewport 49 of the handle 45, as seen in FIG. 2.

Referring now to FIG. 3, wherein some of the control devices and apparatus contained within the housing 21 is illustrated, the segment 35 of the hot water line is connected to a tee 51. By means of this tee 51, a capillary tube 53, which leads to an adjustable thermostatic switch 55, is joined to the hot water line segment 35. This thermostatic switch may be any suitable type well known in the art having a single-pole, double-throw electrical switching arrangement and a temperature adjustment of a range from about to The desired setting of the thermostat is made manually by an adjustment knob 57.

From the tee 51, the hot water line continues to a tee 59 where the line branches into segment 37, which leads to the faucet 13, and into a branch 60, which leads to a solenoid valve 61. The solenoid valve 61 in turn is connected to the segment 39 of the hot water line, which leads to the drain 19. The solenoid valve 61 may be any suitable electrically operated water valve, such as is conventionally used on washing machines, but should be such that the open flow capacity of the valve is greater than that of the faucet 13. When the valve 61 is open (solenoid energized), water in the hot water line 15 from the segment 35 is discharged directly to the drain 19 and bypasses the faucet 13. On the other hand, when the valve 61 is closed (solenoid de-energized), the water is retained in the hot water line 15 except as may be discharged by the manual operation of the faucet 13.

The thermostatic switch 55 responds to the temperature of the water in the hot water line 15 as sensed through the capillary tube 53. When the water temperature is below the setting of the adjustable knob 57, the solenoid valve 61 is potentially energized, as will be seen hereinafter, and when the water temperature equals or exceeds the setting, the solenoid valve 61 is de-energized, but the ready indicator light 27 is on.

The aforementioned components illustrated in FIG. 3 are all suitably mounted on a base 63 of the housing 21 and supported thereby. Other components of the illustrated embodiment are suitably mounted on a cover 65 of the housing 21 and are illustrated in FIG. 4. For convenience, these components may be formed in a sub-assembly as illustrated by being mounted on an electrical mounting panel 66, which in turn is then appropriately secured to the cover 65.

For clarity of illustration, the electrical wires interconnecting the components of FIGS. 3 and 4 are not illustrated in these figures except for a cord 67 which is connected at one end to a terminal block TB (FIG. 4) and extends from there out through the cover 65. The cord 67 has a suitable plug 69 connected to its free end (FIG. 1), and this plug 69 is inserted in a suitable receptacle 71 wired to a voltage source, such as a nominal l V.A.C. source. Although not shown, the components are interconnected by conventional electrical wiring to form an electrical control circuit in accordance with the schematic illustrated in FIG. 5.

With reference now to the schematic, the nominal 1 l0 V.A.C. is applied across the outside legs of the diagram. An input fuse F is provided to protect the components and will open the circuit in the event of an overload or short in the circuitry. A transformer TR which may be a conventional two-winding isolated primary type step-down transformer, is of a suitable capacity for the load of the circuit, and this load is readily determinable by one skilled in the art. In the illustrated embodiment, when the nominal 110 V.A.C. is applied to the primary, approximately 12 V.A.C. is available at the secondary terminals as indicated. Such low voltage secondary is among ratings commonly used for control and signal circuits, and, of course, it reduces the hazard for personnel.

The start switch-25, which preferably is of the momentary push-button type and is normally open, is wired across the 12 V.A.C. in series with the coil of a relay R and of the operating coil of a timer T in parallel.

with the relay R. Upon depression of the start switch 25, the circuit is closed and the voltage appears across the coils and energizes the relay R and starts the timing of the timer T. The relay R includes a set of normally open holding or maintain contacts R-l that close when the relay R is energized. The timer T includes a set of normally open contacts Tl that close when the timer starts timing and open when the timer times out. It will be noted that these contacts R-1 and T-l are wired in series with each other and are in a circuit portion that is across (shunts) the start switch 25. This circuit portion is generally indicated by the reference number 72 and is referred to hereinafter as the holding circuit. In the normal condition, this holding circuit is open or incomplete, but upon the momentary depression of the start switch 25, both the relay R and the timer T become energized and the contacts R-1 and T-l close to complete the holding circuit. The holding circuit then maintains voltage across the coils on the relay R and the timer T after the start switch 25 has returned to its normal condition (open). The voltage is maintained across these coils, however, only so long as certain other conditions also are satisfied in the holding circuit 72.

In series with the contacts R-1 and T-l in the holding circuit 72 is a cancel switch 29, which also is preferably of the momentary push-button type, but is normally closed. Thus, unless this switch is depressed, such as when it is desired to cancel a cycle in process, the circuit is always complete through this switch. Also in series in this holding circuit are the contacts of the adjustable thermostatic switch 55. Preferably this thermostatic switch is of the conventional single-pole, doublethrow type.

As mentioned previously in connection with FIG. 3, the thermostatic switch 55 senses the temperature of the water in the hot water line through the capillary tube 53. For convenience of illustration, the throw of the contacts is illustrated schematically by an armature 73, and this armature moves to either of its two positions in response to the temperature of the hot water. When the temperature of the Water in the hot Water line 15 is below the selected temperature setting of the knob 57 of the thermostat, the armature 73 will be in its upper position and close the holding circuit, as indicated in FIG. 5. On the other hand, when the water temperature exceeds the selected temperature setting of the knob 57, the armature will drop to its lower position, as indicated in phantom. The dropping of the armature breaks (opens) the holding circuit and the voltage is removed from the coils of the relay R and the timer T. Although the armature 73 breaks the holding circuit 72, it makes another circuit in its lower position and applies the voltage to the ready indicator light 27.

Thus, once the momentary start switch 25 is depressed and the coils of the relay R and the timer T are energized, voltage will be maintained across these coils by the holding circuit 72 until the first of any of the following occurs: (a) the timer T times out and opens its contacts T-l, (b) the cancel switch 29 is manually actuated (depressed), or (c) the water temperature exceeds the selected temperature setting on the thermostat 55.

The primary function of the relay R is that of controlling the solenoid valve 61, and it does this by a second set of normally open contacts R-2, which are wired in series with the solenoid. When the relay R becomes energized, the contacts R-2 close and apply voltage to the solenoid coil of the solenoid valve 61, and the energized solenoid opens the valve (the solenoid valve 61 is an electromechanical device). As a consequence of the open water valve, water from the hot water line 15 is discharged directly to the drain 19 via the hot water line segment 39 (FIGS. 1 and 3) and bypasses the faucet 13. This discharge of water drains the hot water line 15 of water having a temperature below (cooler than) the temperature setting on the thermostat 55. If ever the hot water in the primary water heater (not shown) is depleted, continous draining of the line is automatically prevented by the timer T, which after a preset time lapse opens the contacts T-l to de-energize the relay R and the solenoid and close the water valve. Preferably, the timer T has a time period of at least three minutes and also is provided with means for adjusting the time period. A longer maximum period is also satisfactory as long as the increments of adjustment are reasonably fine. Of course, as mentioned previously, the operation also can be interrupted at any time by a momentary actuation of the cancel switch 29.

A cycle of operation begins with the depression of the start switch 25. Thereafter, under normal circumstances, the cooler water is drawn from the hot water line 15 until the hotter water is sensed near the discharge point by the thermostat 55, which then responds by moving the armature 73 (common contact) from its position at the upper pole, as viewed in FIG. 5, to its alternative position at the lower pole. This action opens the circuit to the relay R and the timer T and closes the circuit to the ready indicator light 27. The water automatically stops draining, and the system awaits further action by the user, indicating its ready state at the light 27 (FIG. 1).

The light 27 will remain on as long as the water temperature exceeds the preset temperature on the thermostat 55. When the water cools and its temperature drops below the thermostat setting, the armature 73 returns to its normal position at the upper pole, shutting off the light 27 and potentially completing the holding circuit 72. The contacts R-1 and T-l are both open at this time, however, and the relay R is not energized by this armature movement. Hence, the solenoid valve 61 is not reactuated to reinstate draining. The circuit, of course, could be easily arranged to automatically reinstate the drain cycle every time the hot water temperature falls below the thermostat setting and thus maintain the ready state of warm water at the discharge point. In most domestic situations, however, the relatively infrequent use of water would not seem to warrant the added loss of water, a by-product of the more frequent line draining that would occur in maintaining a given water temperature at the discharge point. Hence, it is preferable to recycle only upon user demand rather than automatically.

In accordance with the principles of the present invention, the illustrated embodiment, including the solenoid operated valve 61 and its control, provides significant advantages over the manual running of hot water through a faucet to obtain water of a comfortable temperature for personal use. As previously indicated in the manual system, the user occasionally tests the discharge and perceives through his own senses when the water is ready for use. In so doing, he possibly will overshoot his requirement and obtain water hotter than desired, in which circumstance more water than necessary is used and momentary personal discomfort may occur.

In contrast, the illustrated embodiment provides for sensing the water temperature accurately and automatically, the water valve automatically stopping the water discharge immediately upon the water temperature reaching the preset temperature, The system then indicates its ready condition. This in itself is advantageous, for only the required amount of water needed to reach the ready condition is discharged, and the user is free for other activities during this time, once he has initated the cycle. In accordance with other features of the present invention coupled with the foregoing, however, further advantages will also become apparent. The other features and advantages are best illustrated by way of the example in the following paragaphs.

Two separate tests were conducted under comparable conditions, utilizing in one test the solenoid oper ated valve 61 and the control circuit and apparatus of the illustrated embodiment. In the other test, the faucet 13 without the solenoid valve but with the balance of the control circuit and apparatus was utilized. The temperatue settings on the primary hot water heater (not shown) and the adjustable thermostatic switch 55 were l40F and l30F respectively. These temperature settings are provided for illustrative purposes only, it being understood that other settings, particularly those above l40F on the primary heater and those below l30F on the switch 55, would also evolve the same principles, though not the same vlues, exemplified hereby. Both tests were conducted with the drain line opened so that the discharged water could be collected and measured. Both tests were conducted after the water had stood in the line for approximately 4 hours.

In the test utilizing the solenoid operated valve 61, the start switch 25 was depressed, and the water that flowed was collected until the ready light 27 was energized. The collected water was measured, and the time interval between depressing the switch and the energizing of the light was noted.

In the other test utilizing the faucet 13, the faucet was manually opened to the full flow, hot water position,

and the water that flowed was collected until the ready light 27 was energized. The collected water was measured, and the time interval between the opening of the faucet and the energizing of the light was noted.

In the test utilizing the solenoid operated valve 61, a flow rate of 3.0 gallons per minute and a time interval of approximately 27 seconds were recorded. The volume of water measured was approximately 11 pints.

In the test utilizing the faucet 13 rather than the solenoid operated valve 61, a flow rate of 1.8 gallons per minute and a time interval of approximately seconds were recorded. The volume of water measured was approximately l6 pints,

The above results were obtained by utilizing a solenoid operated valve 61 having a flow coefficient significantly greater than the flow coefficient of the faucet l3, and the combination of the illustrated embodiment including this important feature provides an unexpected result that is exemplified in the foregoing test results. The length of pipe between the primary hot water heater and the point of discharge is unchanged in these tests, and it would appear that the volume of water discharged in draining the line until water of the preset temperature reaches the discharge point should be substantially the same and independent of the flow rate in the line. Yet it will be observed that the volume of water so drained is considerably less in the instance of the test which has the higher flow rate and lower time interval resulting from the use of the higher flow coefficient solenoid operated valve 61.

While not wanting to be held to a precise theory of why the above-indicated volume of water is significantly less, one possible explanation includes the application of a heat transfer proposition which states that an increase in the average velocity of a fluid past a surface is accompanied by an increase in the individual coefficient of heat transfer across the laminar film of the fluid adjacent the surface. In the above instance of the test utilizing the solenoid operated valve 61, such increase in the coefficient of heat transfer results in an increase in the rate of flow of heat from the water to the wall of the pipe carrying the water. Through the pipe wall, and on the outside of the pipe where heat is transferred to the surrounding air, there is not a corresponding increase in the coefficients of heat transfer, so heat does not flow away from the inner surface of the pipe at the same increased rate that it flows to the surface. Consequently heat is retained at the surface and the inner surface temperature rises at an increased rate. The length of the pipe is unchanged between the two tests, and the heat flow from the water diminishes as the temperature of the inner surface approaches the temperature of the water until the temperature of water arriving at the thermostat is above the selected setting. Hence, with a fixed surface area of heat transfer (fixed length of pipe) and a fixed temperature rise, the pipe that achieves the temperature rise faster, as where the higher rate of water flow occurs, drains less total heat from the water. Stated otherwise, the pipe has a cooling effect on less water, especially the hotter water arriving at the discharge point from the primary hot water heater, and as less water is cooled by the pipe while the water is flowing therethrough, less water needs to be drained from the line to overcome the heat loss that occurs solely during the flow of the water in the pipe.

The desirability of conserving water in this day of environmental concern is selfevident, and so the advantages of these features of the present embodiment in providing significant savings in the total volume of water utilized for personal convenience, as well as a savings in time nd effort of the user, will be readily appreciated. I i

The inclusion of the indicator type blending faucet 13 in the combination of the illustrated embodiment provides another important feature of the present invention. The blending faucet 13 has provision for setting the proportions of the hot water and the cold water which are to constitute the blend. This setting can be predetermined in accordance with principles of the present invention that are hereinafter set forth, and these principles also provide for predetermining a setting for the thermostat 55 that is to be correlated with the faucet l3 setting to provide a continuing flow of water at a comfortable temperature for personal use.

Of course, a number of variables are involved in this system. For example, when water is drawn from the line after the system has reached the ready state, the temperature of the water discharged from the faucet will be unstable for a while. This occurs because the initial temperature in the hot water line near the faucet in the ready state is at the setting of the thermostat 55, whereas the temperature of the water of the primary hot water heater is likely to be substantially higher than this setting. As water is drawn from the line, the temperature of the discharged water then rises until it approaches that of the water of the primary hot water heater. The total range of temperature in the hot water line starts from room temperature before the ready state condition is reached and extends to the temperature of the water of the primary hot water heater. Such range might be, therefore, from about 68F to about 160F. The temperature of the water in the hot water line then stabilizes at the faucet once it reaches the temperature of the water of the primary hot water heater.

Another variable condition exists in the cold water line where the water is likely to have a temperature range extending from the temperature of the water source to room temperature. This range might be from about 40F to about 70F in the winter, and from about 70F to about 78F in the summer. The temperature of the water in the cold water line then stabilizes at the faucet once it reaches the temperature of the water of the source.

in accordance with the foregoing, the initial water in the cold water line is usually warmer than the following water, and the initial water in the hot water line is usually cooler than the following water. From this it will be understood that a blend of such hot and cold water will be unstable for a time. I

To accommodate this unstable condition and yet supply a blend of water falling within a comfortable temperature range for the user, a procedure is hereinafter given for predetermining the preferred settings of the adjustment knob 57 and the faucet handle 45 to provide such. The various temperatures are set forth herein in mathematical terms, the relationships of which are best expressed in the following equations:

Equation (1) represents the initial heat balance of the system in the ready state, and equation (2) represents the heat balance after the water temperatures have stabilized in the system. The flow rate of warm water is taken as 1.0 and may be in any units of volume and time. The flow rate of hot water is represented by X, which is a fraction of the warm water flow rate 1.0). Then the term 1-X) is the flow rate of cold water, also expressed as a fraction of the warm water flow rate. T,, represents the initial temperature of the hot water at the faucet when the faucet is first opened, and T,,' represents the final temperature of the hot water at the faucet after the temperature has stabilized. T, represents the initial temperature of cold water at the faucet when the faucet is first opened, and T represents the final temperature of the cold water after the temperature has stabilized. T represents the initial temperature of the blended water, and T represents the stabilized temperature of the blended water.

It should be understood that in the complete equation, consideration should be given to the density of the water and to the specific heat of the water. For purposes of the present invention, however, the influence of these factors in the aforementioned equations is negligible, and for ease of illustration, these factors have been omitted from the equations.

The stabilized temperature of the hot water (T,,') is assumed to be equal to the temperature of the primary hot water heater, for the temperature of the pipe walls will have risen to steady state condition when the faucet water temperature has stabilized and it is assumed that any temperature drop of the water in transit to the faucet is negligible. The temperature of the water of the primary hot water heater typically ranges from about 140F to about 160F.

The desired warm (blended) water temperature (T and T is approximately F, it having been determined that the comfortable range for human use is from about 95F to about F.

As mentioned previously, the temperature of the water in the cold water line (T and T also is likely to change during the blending process, and the effect of such change is to offset the normal change in temperature that occurs in the water of the hot water line. For example, the cold water may warm up to about 70F as it stands in the pipes located in the heated areas of a building, and then as the water is drawn at the discharge point, the temperature of the cold water at that point will lower. This change in the cold water temperature will vary seasonally and geographically. For purposes only of the present description, a geographical situation is assumed in which the stabilized cold water temperature would be about 70F in the summer and about 40F in the winter. In the summer then, there will be relatively little difference in temperature between the initial water drawn and the stabilized temperature of the water, whereas in the winter, the initial temperature will approximate that of the heated building, for example, 70F, and the stabilized temperature would approach 40F.

The blending faucet l3 and the thermostatic switch 55 control the present hot water system 9 by determining three of the variable terms of the aforementioned equations, namely X (flow rate of hot water), (l-X) (flow rate of cold water), the T,, (initial temperature of the hot water near the faucet).

In the present procedure, equation (2) is first solved to determine the setting for the faucet 13 that will provide a blending of hot and cold water for a final maximum stabilized comfortable temperature that does not exceed the maximum comfortable temperature of l05F. For purposes of the present calculation, assume a thermostatic temperature setting on the primary hot water heater of 140F, which becomes the stabilized temperature of the hot water (T Assume also a large change in the cold water temperature so that T. 70F and T 40F. Substituting these values and solving equation (2):

140(X) 40(lX) 105 This solution determines the faucet setting at the handle 45, and the indicated proportions are for a setting of 65 percent hot water and 35 percent cold water.

Next, equation l) is solved to determine the setting of the knob 57 of the thermostat 55 that will correlate with the above faucet setting to provide initial blended water within the comfort range of 95F and 105F. For this purpose, the mid-range of 100F value is taken. This the unknown in this equation is T (initial hot water temperature). Substituting and solving equation Thus, with an initial hot water temperature of ll6F and an initial cold water temperature of 70F blended in proportions of 65 percent hot water and 35 percent cold water, the initial warm water temperature will be approximately 100F, and the final stabilized warm water temperature, i.e., as the l40F temperature of the water from the primary hot water heater and the 40F temperature of the cold water source reach the faucet, the final stabilized temperature will not exceed 105F, or the upper range of the comfortable warm water.

The lowest setting of the thermostat 55 anticipated in a normal situation would occur in the winter in combination with water from a primary hot water heater having a relatively low temperature setting. Conversely, the highest setting of the thermostat 55 anticipated in a normal situation would occur in the summer in combination with water from a primary hot water heater having a relatively high temperature setting. Thus, lower settings of the knob 57 on the thermostat 55 will be called for when solving the above equations with values reflecting, for example, a water temperature in the primary hot water heater of 140F along with cold water temperatures of approximately 70F initially and 40F stabilized. In like manner, on the other hand, higher settings of the knob 57 will be called for where the values reflect, for example, a water temperature in the primary hot water heater of 160F along with cold water temperatures of approximately 78F initially and 70F stabilized.

It is contemplated that solutions to equations l) and (2) broadly including various combinations of hot and cold water temperatures likely to occur in most geographical areas could be set forth in tabular form to provide the user with ready-made settings for any given situation. Such a universal tabulation would be quite detailed, however, and there might be a drawback in the use of such a tabulation. It may be difficult for users on some geographical areas to obtain sufficient local data on cold water to make good use of the tabulation. Hence, it is believed practical to reduce the present procedure to a set of simplified instructions for use with only a few variables selected so as to provide for optimum general use.

In implementing a procedure for deriving these simplified instructions, a constant cold water temperature of F and a maximum stabilized temperature of the blended water of lO5F are assumed. The solutions then will depend upon the value of the only variable. water temperature of the primary hot water heater. When these values are substituted in equations l and (2), the solutions obtained from solving the equations indicate the settings of the thermostat 55 and of the faucet 13 that will prevent the blended water from exceeding the high end of the personal comfort range. Whenever the stabilizedtemperature of the cold water is lower than the above assumed temperature of 70F, as in the winter, the effect will only be to lower the stabilized temperature of the blended water in the comfort range.

To illustrate a sample derivation of these simplified instructions, the following computations assume a primary hot water heater setting of 140F. Accordingly, the solutions to the equations (1) and (2) are:

X .50 (hot water proportion) (1-X) .50 (cold water proportion) T,,(.50) 70(.50)=100 T (setting of knob 57) Similarly, it can be shown that for a primary hot water heater setting of F, X 0.39 (hot water proportion), (1X)=O.6l (cold water proportion), and T,, M6 (setting of knob 57). It also can be shown that the final cold water temperature T. could drop to almost 50F from the initial 70F before the stabilized blended water will drop below the indicated comfortable range of 95F of 95F to 105F. For the situations where these simplified instructions may not be entirely adequate, as in very cold climates, it can be shown that further computations utilizing equations (1) and (2) as hereinbefore set forth could be made to establish further instructions for correctional adjustments that would overcome a particular condition or conditions.

Referring now to FIG. 2, the setting of the handle 45 of the faucet 13 can be determined by reading the indicia through the viewport 49 in the handle. As mentioned previously, such indicia may be in the form of a color code, although other forms could be suitable for the purpose.

To use and operate the system 9, the user determines the temperature setting of his primary hot water heater and in accordance with the foregoing simplified instructions, sets the knob 57 of the thermostat 55 (FIG. 3) for the appropriate temperature. Also from these instructions, the appropriate proportional setting for the faucet handle 45 of the faucet 13 is determined and made. Once these settings are established for a given situation, they usually will remain the same and need not be constantly reevaluated.

Next, the user momentarily depresses the start switch 25 to begin the automatic cycle. After the ready indicator light is energized, the user obtains blended water within the personal comfort range immediately by opening the faucet 13 at the determined position of the handle 45, the faucet supplying the hot and cold water in previously established proportions according to the instructions. Water then continues to flow within the comfortable temperature range. Usually, no further adjustments need be made, but if the local conditions are such that the simplified instructions fail to provide water totally within the comfort range. appropriate adjustments can be implemented to compensate for these local conditions.

Thus, there has been provided in accordance with the present invention, a hot water system 9 wherein apparatus and an automatic control therefor provide for draining the hot water line until water having a predetermined temperature is available at a faucet or other discharge point, and wherein the water drained from the line in reaching this predetermined temperature is kept to a minimum volume. Moreover, in conjunction with a proportional setting blending faucet and in accordance with the principles and procedures herein set forth the present system further provides blended water within a predetermined temperature range, both initially and in a continuing stream, at the discharge point, both during and after the temperature of the water in each line stabilizes.

While the invention has been described in connection with a preferred embodiment, many alternatives, modifications, and variations may be apparent to those skilled in the art in view of the foregoing description and illustrations. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and scope of the appended claims.

Various features of the invention are set forth in the following claims.

What is claimed is:

l. A hot water system comprising a drain, a hot water line, a faucet having a given flow capacity and disposed in said line, a valve disposed in said line ahead of saidfaucet and arranged to cause water in said line to bypass said faucet and be discharged directly to said drain from said line when said valve is open, said valve being electrically operated and having a flow capacity greater than that of said faucet, a manually actuated switch for selectively causing the opening of said valve, means for sensing the temperature of the water in said line, control 2. A system in accordance with claim 1 and including a cold water line, said system further comprising single operating means associated with said faucet for adjustably blending water from the hot and cold water lines in predetermined portions for discharge from said faucet.

3. A hot water system comprising a drain, a hot water line, a faucet in said line, an electrically operated valve disposed in said line ahead of said faucet and arranged to discharge water from said line directly to said drain and bypass said faucet when said valve is open, a manually actuated switch for selectively causing the opening of said valve, means for sensing the temperature of the Water in said line, control means responsive to said temperature sensing means for causing the closing of said valve when a predetermined water temperature is reached, and means for providing a signal when said predetermined temperature is reached.

4. An electrical circuit for controlling the temperature of water discharged from a hot water line, said circuit comprising a stepdown voltage transformer, relay on the low voltage side of said transformer, a normally open momentary type pushbutton switch for energizing said relay, a normally closed momentary type pushbutton switch for de-energizing said relay, an adjustable thermostatically controlled switch responsive to the temperature of the water in said hot water line for deenergizing said relay when a predetermined water temperature is reached solenoid valve means responsive to said relay, and means for providing a signal responsive to said thermostatic switch for indicating when said predetermined temperature of the water is reached.

5. An electrical circuit in accordance with claim 4 wherein said switching means further includes timer means for controlling said relay.

O UNTTED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3 5 5 4 DATED I May 27, 1975 V 1 Walter L. Hock Page 1 of 2 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 7, lines 36 and 37, "initated" should be initiated.

Col. 7, lines 47 and 48, "temperatue" should be temperature.

. Col. 7, line 55, "vlues" should be --values-.

I Col. 8, line ll, "65" should not be in bold type.

Col. 9, line 4, "nd" should be and--.

. i Col. 9, line 63, "Th" should be -'I Col. 9, line 66, "Th" should be T Col. 10, line '67, "the" should be and.

Col. 11, line 26, "This" should be Thus-.

Col. 11, line 31, "T 116" should be inserted below "T (0.65) 70 (0.35) 100" (line 30) Col. 12, line 2, "on" should be -in-. Col. 12, line 31, (l) before the second equation is P missing. Col. 12, line 40, delete second occurrence of "of 95F".

Col. 14, Claim 1 should be completed by adding: v (see page 2) O UNITED STATES PATENT AND TRADEMARK OFFICE CETIFICATE OF CORRECTIQN PATENT NO. 3,885,584

DATED May 27, 1975 p 2 f 2 |N\/)ENTOR(5) Walter L. Hock it is certified thaierror appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

"means responsive to said temperature sensing means for causing the closing of said valve when a predetermined water temperature is reached, and means for providing a signal when said predetermined temperature is reached."

Col. 14, line 33 (Claim 4) a comma should be inserted after "reached".

Signed and Scaled this seventeenth D ay Of February 1 976 [SEAL] Arrest:

RUTH C. MASON Arresting Officer 

1. A hot water system comprising a drain, a hot water line, a faucet having a given flow capacity and disposed in said line, a valve disposed in said line ahead of said faucet and arranged to cause water in said line to bypass said faucet and be discharged directly to said drain from said line when said valve is open, said valve being electrically operated and having a flow capacity greater than that of said faucet, a manually actuated switch for selectively causing the opening of said valve, means for sensing the temperature of the water in said line, control
 2. A system in accordance with claim 1 and including a cold water line, said system further comprising single operating means associated with said faucet for adjustably blending water from the hot and cold water lines in predetermined portions for discharge from said faucet.
 3. A hot water system comprising a drain, a hot water line, a faucet in said line, an electrically operated valve disposed in said line ahead of said faucet and arranged to discharge water from said line directly to said drain and bypass said faucet when said valve is open, a manually actuated switch for selectively causing the opening of said valve, means for sensing the temperature of the water in said line, control means responsive to said temperature sensing means for causing the closing of said valve when a predetermined water temperature is reached, and means for providing a signal when said predetermined temperature is reached.
 4. An electrical circuit for controlling the temperature of water discharged from a hot water line, said circuit comprising a stepdown voltage transformer, relay on the low voltage side of said transformer, a normally open momentary type pushbutton switch for energizing said relay, a normally closed momentary type pushbutton switch for de-energizing said relay, an adjustable thermostatically controlled switch responsive to the temperature of the water in said hot water line for de-energizing said relay when a predetermined water temperature is reached solenoid valve means responsive to said relay, and means for providing a signal responsive to said thermostatic switch for indicating when said predetermined temperature of the water is reached.
 5. An electrical circuit in accordance with claim 4 wherein said switching means further includes timer means for controlling said relay. 